Definition of laser parameters

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Photonics Dictionary

laser parameters: Laser parameters are the characteristics that define the behavior and performance of a laser. These parameters can be categorized into several groups: spatial, temporal, spectral, and operational.

Spatial parameters:

Beam diameter: The width of the laser beam, usually measured at the point where the intensity falls to 1/e² (about 13.5%) of its maximum value.

Beam divergence: The angle at which the laser beam spreads out over distance. It is often measured in milliradians (mrad).

Beam quality (M² factor): A measure of how close the laser beam is to an ideal Gaussian beam. An M² value of 1 indicates a perfect Gaussian beam.

Temporal parameters:

Pulse duration: The length of time a laser pulse lasts. It can range from femtoseconds (fs) to continuous wave (CW).

Pulse repetition rate: The number of laser pulses emitted per second, measured in Hertz (Hz).

Spectral parameters:

Wavelength: The distance between successive peaks of the laser wave, typically measured in nanometers (nm) or micrometers (µm).

Bandwidth: The range of wavelengths over which the laser emits. This can be very narrow for single-wavelength lasers or broad for tunable lasers.

Linewidth: The spectral width of the laser emission at a specific wavelength, usually measured at half the maximum intensity (full-width at half-maximum, FWHM).

Operational parameters:

Power: The output power of the laser, typically measured in watts (W) for continuous wave lasers or in joules (J) for pulsed lasers.

Energy per pulse: The energy delivered in a single laser pulse, usually measured in joules (J).

Efficiency: The ratio of the output power to the input power, expressed as a percentage.

Mode: The spatial distribution of the laser beam’s intensity. Common modes include TEM00 (Gaussian) and higher-order modes.

Additional parameters:

Coherence: The degree to which the laser waves are in phase with each other over time (temporal coherence) or space (spatial coherence).

Polarization: The orientation of the electric field of the laser beam. Lasers can emit linearly, circularly, or elliptically polarized light.

Environmental parameters:

Operating temperature: The temperature range within which the laser can operate effectively.

Cooling requirements: Lasers often need cooling mechanisms to dissipate heat generated during operation.

Safety parameters:

Class: Lasers are classified based on their potential hazard, from Class 1 (safe under all conditions) to Class 4 (dangerous and can cause severe damage).

These parameters are critical for selecting the right laser for specific applications, such as medical treatments, communication, manufacturing, or scientific research.

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